kiwis:
I thought that if you changed motherboards you just needed to contact MS? Assume this is what the earlier post about phoning up was about?
I used this disk to install Windows on a laptop a year ago, no issues. So I assume the disk will work.
If your using an older W10 DVD disk then there will be several updates post that as it trys to update but will work.
Yes try your key and if no luck ring MS and they will help you activate it.